In order to increase the life of grease lubricated bearings that are operated at high temperatures, high speeds, or both, various additives and thickeners are added to the bearing lubricants. It has been found, for example, that some compounds that have a lattice structure are good additives for lubricants. These include the selenides and sulfides of tungsten, molybdenum, tantalum, and niobium However, it has also been found that compounds that are chemically similar and that also have a lattice structure have a very poor lubricating ability. For example, tellurium is chemically very similar to selenium, but the tellurides of tungsten, molybdeneum, tantalum, and niobium are very poor lubricants. Other compounds that have a lattice structure, such as calcium fluoride, are also poor lubricants, and titanium sulfide, which also has a lattice structure, is actually abrasive. Thus, it is difficult to predict from the chemical structure alone whether or not a compound that has a lattice structure will actually perform well as a lubricant.